Transmitters or transceivers often use a power amplifier to increase the amplitude of a radio frequency (RF) signal that is provided to an antenna for transmission. In most applications, it is desirable to operate the transmitter as efficiently as possible, that is, by achieving the highest RF output power relative to the power being provided out of the energy source, such as a battery. One method of improving amplifier efficiency is by controlling the overall power output capability or headroom of the power amplifier. For example, an additional decibel (dB) of headroom (the amount by which the power output capability exceeds the actual power of the output signal) produces an efficiency loss of around ten percent. Thus, most systems attempt to keep the headroom to a minimum amount necessary in order to reduce the current drain of the amplifier and improve overall efficiency.
In many current systems, the amplifier headroom or power output capability is controlled in real-time based on power level commands for a current time interval. Sufficient power amplifier headroom is critical in meeting spectrum emission requirements and maintaining amplifier efficiency. However, most hardware currently used to control the amplifier headroom is not capable of making large adjustments to the power output capability in a limited amount of time. Thus, current systems may either fail to provide adequate headroom, or alternatively, provide too much headroom when confronted with a rapid change in output power level. This, in turn, leads to either clipping and/or distortion of the RF signal (e.g., in the case of inadequate headroom) or reduced amplifier efficiency (e.g., in the case of too much headroom).